Many people are working to harness renewable energy sources more effectively and to enhance energy efficiency. All good. Most of the efforts will probably result in welcomed but incremental improvements, however. Radical innovations are needed to drastically change the energy game.

For years scientists and engineers have touted some fantastic schemes: satellites that beam solar power to receivers on land; wind machines that hover in the atmosphere, generating electricity. Down on earth, however, researchers have recently received substantial government or private funding for a remarkable variety of long-shot technologies in a few key areas. The projects we profile here are leading examples of the payoffs that are possible—if, of course, the inventors manage to overcome daunting hurdles to bringing practical, mass-produced and affordable technologies to fruition.